Jarring tool



` March; .7.;1-1196711 J. v, LE BLANC JARRING TOOL s sheets-sheet 1Filed. June 29 1964 l March 7, 1967 J. v. LE BLANC JARRING TOOL 3Sheets-Sheet 2 Filed June 29, 1964 y 3 w C m. M r f m T H m m Z wm f A,n f w m d 2 w d M b,\ A ,n M w MV/MVVV/ /v 1 Y ,I r I M v 9 fmch 7,1967 J. v. LE BLANC JARRNG TOOL 3 Sheetivheet 5 Filed June 29, 1964INVENTOR.

United States Patent Gilice 3,307,636 Patented Mar. 7, 1967 3,307,636EARRING 'I'OL Joseph V. Le Blanc, 102 N. Delmont E., Conroe, Tex. 77301Filed .lune 29, 1964, Ser. No. 378,598 9 Claims. (Cl. 173-13) Thisinvention relates to a tool commonly known as a hydraulic jar, and moreparticularly it relates to a hydraulic jarring tool adapted to bepermanently positioned in an oil well drill string for the purpose ofproviding at desired times automatically repeating impacts on the drillstring.

In the drilling and maintenance of oil wells it is frequently desirableor necessary to apply a series of impacts or vibrations to equipment inthe Well bore. For example the drill bit or `the drill collars above thedrill bit may become stuck in the drill hole due to caving in of theformation being drilled or to some other cause. As a result the drillbit or other piece of equipment cannot be turned or withdrawn byordinary pulling or rotation of the drill string to which it isattached. For the purpose of freeing such stuck or jammed equipment,various types of jars have been developed. Most of the jarring toolsheretofore devised are used to transmit a relatively powerful blow atvery low frequency to the stuck equipment. In addition most such priorart jarring tools require releasing of the tool between blows so thatany gain made by the blow in pulling the tool may be lost` when the toolis released between blows. Such tools must be reset after each 'blow inorder to effect another blow.

In addition-jarring tools heretofore used have been of such design thatthey could not remain permanently in the drill string but must be addedto the drill string when jarring is required.

An object of this invention is the provision of a well jar for producinga series of sharp impacts in rapid succession.

Another object of this invention is the provision of a vibratory welljar which is hydraulically operated by the ordinary drilling mud used inthe drilling operations.

Another object of the invention is the provision of a hydraulicvibratory well jar which permits a continuous upward strain o r pull tobe maintained on the stuck equipment throughout the period of timeduring which jarring is taking place.

Still another object of this invention is to provide a jarring toolwhich may be permanently placed in the drill string and which has a fullopening therethrough for normal passage of drilling mud or tools throughthe jar.

Another object of the invention is to provide a jarring tool which isactuated solely by the application of a strain to the drill string andthe normal pumping of drilling mud into the drilling string, and whichautomatically repeats without any manipulation to reset it Ibetweenimpact blows.

According to this invention these and other objects are accomplished bymeans of a hydraulic jarring tool which is automatic in operation, inthat the drill pipe need not be raised and lowered at the surfacebetween blows of the jar. Jai-ring is accomplished by hydraulicallyelongating the drill string with increased fluid pressure within thetool, and quickly releasing the pressure and allowing the elasticity ofthe drill string to contract the string and pull the impact surfacestogether at high velocity so as to cause a jar to the stuck portion ofthe drill string. In a preferred embodiment, this tool comprises a pairof telescopically engaged tubular elements which are connected in thedrill string. One of the tubular elements, which for example maycomprise a housing, is attached to the drill string below the jarringtool and the other tubular element, which may comprise a mandrel, isattached to the drill string above the jarring tool. The mandrel has afluid passageway therethrough which is preferably of substantially thesame size as the passageway through a drill collar so that there is norestriction of ow through the jarring tool. In normal drillingoperations the housing and mandrel are in engagement with each other sothat they can rotate together, whereby drilling torque may betransmitted through the jarring tool. The mandrel and housing are eachprovided with impact faces which strike each other to cause the jarringaction. In the preferred embodiment, the housing and mandrel aresealingly engaged with each other, and an annular space is providedbetween them to receive drilling mud under pressure. A valve mechanismcarried by the mandrel may be actuated when tension is applied to thedrill string to cause drilling mud to ilow into the annular space andthereby force t-he mandrel and housing to move longitudinally withrespect to each other so as to increase the tension on the drill string.Then at a predetermined point the valve is operated to release thedrilling mud from the annular space so that the tension built up in thedrill string causes the mandrel and housing to move longitudinally inthe opposite directions whereby the impact surfaces strike each other tocause a jar. Upon striking each other the valve is again actuated todivert the flow of drilling mud. Thus it is seen that the tool is ableto automatically repeat the blows of the impact faces without anymanipulation from the surface between blows.

For a better understanding of the invention reference is now made to theaccompanying drawing wherein VFIGURES 1A, 1B, 1C, and'lD arelongitudinal sections of successive portions of a preferred embodimentof the jar of this invention; i FIGURE 2 is a horizontal section of theembodiment ofthe jar shown in FIGURES 1A to 1D, taken at line 2--2 ofFIGURE 1B;

FIGURES 3A and 3B are longitudinal sections of successive portions ofthe embodiment of FIGURES lA to 1D but shown at a different stage of theoperation of the jar; and

FIGURE 4 is a horizontal sectional view of the tool in the stage ofoperation shown in FIGURES 3A and 3B, taken at line 4-4 of FIGURE 3A.

FIGURES 1A to 1D and 2 show a preferred embodinient of the invention asit appears when no jarring is taking place. As shown in FIGURE 1A thetool of the embodiment shown is attached to a drill string by means of atool joint pin 10 at the upper end of the tool and a tool joint box 12at the lower end of the'tool. The pin and box 10 and 12 are respectivelyattached to the drill string above the jarring tool and the drill stringbelow the jarring tool. Usually the box 12 will be at the upper end of astring of drill collars.`

In the embodiment shown in the drawing, a mandrel 14, having a maximumdiameter substantially no greater than the diameter of the tool joint10, is threadedly secured to the tool joint pin, and is also attached,as by means of readily releasable threads such as square threads 16, toa housing 18. Housing 18 also has a maximum diameter substantially nogreater than the diameter of a tool joint or drill collar in the drillstring. In the embodiment shown, the threads 16 are shown as beingfemale threads on the mandrel 14 and male threads on the housing 1S,although they may of course be reversed if desired. As shown in thedrawing, the portion of the housing 18 about which threads 16 extend isofreduced diameter, forming Ian inwardly extending annular shoulder 19,and is provided with internallyv facing packing members 20 whichsealingly engage a cylindrical portion 22 of the mandrel which istelescopically received inside the housing. An annular space 24 isformed between the main ybody of the housing 18 and the major portion ofthe mandrel 14 which is received within the housing.

At itsv lower end the cylindrical portion 22 of the' man-v drel isthreadedly engaged in a valve lbody 26 Which is carried on and forms apart -of the mandrel 14.4 At its lower end the valve body 26 isconnected to another tubular portion 28 of the mandrel, which extendsbelow the valve body longitudinally within the -housing 18.V The valvebody 26 is preferably not completely cylindrical in shape, but isprovided with flat sides 27 to provide increased fluid flow area, aswill hereinafter appear. The lower end of the tubular portion 28 has apiston 30 formed thereon which sealingly engages the inner wall lof thehousing 18. The lower end of the housing 18 is threadedly engaged with across-over sub 32, which is provided with a tool joint pin 34 adapted tobe connected to tool joint box 12.

The valve body 26 has a ilongitudinal passageway 36 therethrough whichis substantially the same diameter as the lbore through the drillcollars of the drill string, so that flow of drilling fiuid and movementof tools therethrough is not restricted. This passageway is provided ateach yend with threads 38 and 39 for engagement by the tubular portions-22 and 28, respectively, of the mandrel 14. Approximately midway of thelength of the valve body 26, a transverse bore 40 is provided torotatably receive a generally cylindrically shaped valve core 42, theaxis of which extends at right angles to the axis of the passageway 36through the valve body. The valve core 42 'has la transverse passageway44 extending therethrough which is of substantially the same size as thepassageway 36 and, in the position shown in the FIGURES 1A to 1D andFIGURE 2, is substantially in alignment with the passageway 36, so asnot to restrict fiow therethrough. The valve lcore also has a passageway48 which extends axially through the core and is therefore at `rightangle-s t0 the passageway 36. The passageway 48 connects the passageway44 with the annular space 24 between the valve body and the housing 18.This -axially extending passageway 48 may be somewhat smaller than thepassageway 44 andmay, for example, be approximately half the'area of thepassageway 44. The valve corel 4is also provided with a port 46 whichextends -at right langles to each of the 'passageways 44-and 48 andprovides communication of the exterior' of the valve core with theintersection of the passageways 4'4 and 48.v The port 46 does not extendall the way through the valve core as does passageway 44, but only fromthe outside surface to the center.

Each end of the valve core has formed thereon a pair of pins Spositioned approximately 180 apart and extending longitudinally of thevalve core a short distance from the end of the core. A similar pair ofpins 52 are fixed on each side of the valve body 26` with one of eachpair being positioned upwardly from the valve core, and the other ofeach pair being positioned downwardly therefrom substantially centrallydisposed transversely of the valve body. Each of said vpins 52hasmounted thereon a rocker arm 54 adapted to pivot about the axis ofthe pin. Each rocker arm has pivotally attached at one end a connectingrod 56, each connecting rod extending between the upper and lower of onepair of lrocker arms 54 and being pivotally mounted at substantially itscentral point on a pin 50 on the valve core. The opposite end of eachrocker arm is provided with a pin 58 which is slidably received in atransverse slot 60 in a push rod 62'. The other pin 50 on the valve coreis slidably received in a similar slot 64 in the push rod, which slot ispositioned approximately midway between the slots 60 ofthe push rod.

' A push rod 62 -is carried on ea-ch side of the valve body 26 andextends longitudinally thereof. Each end of each push rodvis preferablypositioned substantially centrally laterally of the valve body, but theintermediate portions of the push rods are laterally displaced in orderto suit-Y ably engage the pins 58 on the rocker arms 54. At each end ofthe valve body, a strap 66 attached thereto provides means for guidingthe ends of the push rod.

A valve operating mechanism is positioned just below the valve body andsurrounding the tubular portion 28 of the mandrel 14. The operatingmechanism comprises a cylindrical spring 'housing 68, which is attachedat one end to the push rod's 62 and extends downwardly therefrom insurroundilng relationship with the tubular portion 28 of theimandrel. Atits upper end, the housing 68 has -aninturned flange 70 which fitsaround the tubular portion 28, and at theother end of the housing thereis an inturned flange 72, which sealingly engages the tubular portion28, as by means of packing 74.V i Intermediate the inturned flanges 70and 72, an annular spring collar 76 is formed on the tubular portion 28and sealingly engages the interior of the spring housing 68. A fluidpassageway 98 provides communi-cation between the bore of the tubularportion 28 of the mandrel and the annular space between the inturnedflange 72 and the spring collar 76. A heavy coil compression springbears lagainst the inturned flange 70` and the spring collar 76. Theupper end of the spring housing 68 is therefore biased upwardly towardthe valve body 26 and the push rods 62 are resiliently biased toward theposition shown in FIGURES 1A and 1B.

A plurality of resilient fingers 80 are formed on the lowerend of thespring housing 68 and extend downwardly therefrom, beingcircumferentially spaced around the tubular portion 28 of the mandrel14. Each finger 80 has an outwardly upset portion 82 thereon, forming ashoulder 84 with the mainV body of the finger. At their lower ends, theoutwardly upset portions 82 taper inwardly, and are preferably arcuatelytapered inwardly to a reduced thickne-ss at the extreme end of thefinger. In the position of the tool shown in FIGURES 1A to 1C, andparticularly as shown in FIGURE 1C, the upset portions 82 of the fingersare received within longitudinal openings 86 formed in a' collar 88' onthe tubular'portion 28 of the mandrel. In this same position the lowerend of the upset portions of these fingers is received within a ring 90,which is held in the position shown by means of a plurality of dog pointset screws '92 which engage an annular external groove 94 on the ring.The ring has an annular internal bevel 96 at its upper end for a purposewhich will hereinafter be described. The internal diameter -of the ring98 is no larger than the ex. ternal diameter of the openings 86 in thecollar 88 and preferably is slightly smaller. The resilient fingers 88tend to spring radially outwardly, and therefore bea-r on the bore ofthe ring 98.

In the use of the jarring tool of this invention, it is normallypermanently positioned in the drill string, usually just above the drillcollars. In ordinary drilling, torque will be transmitted through theloose fitting right hand threads 16 connecting the housing 18 and themandrel 14, and thus through the housing 18 into the peru tion of thestring therebelow. Drilling fluid is co cted through the mandrel,including the passageway 44 the valve core, to the drill bit. When thedrill string below the jar becomes stuck so that it cannot be loosenedby either rotationor pulling on the drill string, the string is rotatedc'ounterclo'ckwise at the-surface so as todisengage the threads 16, andallow the mandrel 14 to be-moved longitudinally with respect to thehousing 18. The portion of the drill string above the connection 16 isthen lifted upwardly, suicient force being applied to lift all thatportion of the drill string above the jar.

As the drill string is lifted up, the mandrel 14 will be lifted, alongwith the valve body26 thereon and the tubular portions 22 and 28, aswell as the piston 30 on the lowerend of the mandrel 14. As the valvebody 26 moves upwardly, the push rv-ods 62 will engage the shoulder 19on the housing 18. Further upward movement of the mandrel will causerelative movement between the push rods 62 and the valve body 26, thevalve body moving upwardly relative to the push rods until the upper end100 of the valve body hits the `shoulder 19. It will be apparent thatsuch upward movement of the valve body relative to the push rods will,due to the linkage formed by the rocker arms 54 and connecting rods 56,cause the valve core 42 to be rotated. The proportioning of the linkageand locations of the various pins are such as to cause a rotation of thevalve core of approximately 90 upon movement of the push rods 62 fromthe position shown in FIGURE-1A to a position wherein the upper ends ofthe push rods are substantially flush with the upper end 100 of thevalve body 26. l

Such a 90 rotation of the valve core will cau-se the passageway 44through the valve core to be rotated until its axis is at approximately90 to the axis of the passageway 36 through the valve body. The port 46will, however, then be in communication with the passageway 36. FIGURE 4shows this position of the valve core. Thus, drilling fluid being pumpeddown through the drill string is passed through the port 46, and then atright angle-s thereto through th'e passageways 48 into the annular space24 intermediate the mandrel and the housing 18.

It will be appreciated that the upward movement of the drill string,pulling the valve body 26 up so that the push rods 61 engage shoulder19, also has the effect of moving the lower tubular portion 28 of themandrel upwardly so that the upset portions 82 of the resilient finge-rs80 are pulled out of the ring 90. Then, when the upward movement of thevalve body 26 continues, since the push rods 62 are prevented frommoving upward, the collar 88 is being moved upwardly relative to theresilient fingers 80. The lingers 80 are resiliently biased outwardly,so

that when the collar 88 moves past the shoulders 84 on the fingers, thelingers snap outwardly to lock the shoulder 84 beneath the collar 88.

At the same time, the upward movement of the mandrel with respect to thespring housing 68; causes the spring 78 to be compressed between thespring collar 76 and the inwardly turned flange 70. The relativemovement of the valve operating mechanism and the mandrel also drawsfluid from inside the drill string below the valve to the annular spaceintermediate the housing 68 and the mandrel. It will be appreciated thatthe locking of the upset portions 82 of the resilient fingers behind thecollar 88 holds the spring in compression until the resilient fingersare released.

The flow of drilling fluid through the port 46 and the axial passageway48 through the` valve core and into the annual space 24 causes pressureto be exe-rted against the inturned shoulder 19 and the piston 30 at thelower end of the mandrel 14. Such pressure causes the piston to beforced downwardly. If the drill string is held at the surface againstlongitudinal movement, the force of this pressure will cause elongationof the drill string due to its elasticity. Application of pressure iscontinued until the resilient fingers 80 are moved "down far enough thatthe beveled ends on the upset portions ,engage the bevel 96 on the upperend of the ring 90.

Such engagement with this bevel causes the resilient fingers to beforced radially inwardly. FIGURES 3A and 3B show the tool at the pointwhere the fingers are being pushed inwardly toward the point at whichthey are released from their locked position below the collar 88. Theforce of the compressed spring 78 together with fluid pressure on thelower end of the spring housing 68, thereby causes the push rods 62 tobe moved rapidly upwardly to rotate the valve core back to its originalposition. Fluid under pressure in the annular space 24 may thereforeflow rapidly back through the axial passageway 48 in the valve core andinto the main uid passageway through the valve and valve body.Thissudden release of the pressure in the annular space 24 releases thetension 6 on the drill string thereby allowing the upper end 100 of thevalve body 26 to move upwardly with great force and velocity to strikethe shoulder 19. The striking of these impact surfaces causes a jar tothe stuck portion of the drill string below the jarring tool.

Of course, as soon as the valve body moves upwardly to strike theshoulder 19, the push rods 62 are again engaged by the shoulder 19 toturn the valve core to a position to allow fluid to begin to ow into theannular space 24 so that the operation of the jarring tool isautomatically repeated. Thus, it will be seen that automaticallyrepeating blows of the jar will be achieved by merely applyingsuflicient tension to the drill string to insure that the upper end ofthe valve body 26 engages the shoulder 19 and by continuing the pumpingof drilling mud through the drill string at sufficient pressure toinsure adequate elongation of thedrill string to cause the tapered endsof the resilient ngers to engage the bevel of the ring 90. The weightindicator at the surface will indicate the jarring action by showing agreatly increased weight during the downward movement of the mandrelrelative to the housing and a relaxation of this weight during theVupward movement of the mandrel. The substantial cessation of thisfluctuation in indicate-d load at the 'surface will indicate that thestuck pipe has been loosened. i

Following the loosening of the stuck pipe, the drill bit can be merelylowered to the bottom of the hole, and the telescoping mandrel moveddownwardly into the housing and and then rotated in clockwise directionto fully engage the threads 16. It is not necessary to pull the drillstring from the hole to remove the jarring tool after jarring operationsare completed.

It will be noted that the jarring tool of this invention need not be anylarger in diameter than the drill collars or the tool joints in thedrill string, and yet can provide a full hole opening. The opening maybe designed to be the same diameter as the passageway through the drillcollars, whereby there is no impediment to ow of drilling mud throughthe tool or to the passage of tools therethrough.

The jarring tool of this invention will undoubtedly be found to be mostuseful where drilling mud is being used, but it will also providesatisfactory operation where a gaseous d-rilling fluid is used asopposedy to a liquid.

Many modifications within the scope of the present invention will beapparent to those skilled in the art. For example although theembodiment shown has been described in terms of use for upward jarringonly it will be apparent that this invention can be utilized to obtaindownward jarring o-r both upward and downward jarring. The invention istherefore not limited to the described embodiment but only as defined bythe claims.

What is claimed is:

1. A hydraulic jar comprising a mandrel having a l'irst impact surface,

a housing telescopically receiving said mandrel and having a secondimpact surface adapted to be engaged by said first` impact surface, and

valve means actuable by longitudinal movement of said mandrel withrespect to said housing in one direction to direct uid under pressure tocause said impact surfaces to be moved apart, and actuable bylongitudinal movement of said mandrel in the other direction to releasesaid fluid to allow said impact surfaces to move into engagement witheach other.

2. A hydraulic jar comprising a tubular housing,

means on the lower end of said housing adapted to be attached to a pipestring therebelow,

a downwardly facing inwardly extending `annual anvil y adjacent theupper end of said housing,

a tubular rnandrel telescopically received within said housing andforming an annular space therebetween,

an upwardly facing' annular hammer on'said mandrel,

means sealingly engaging the upper end of said housing labout saidmandrel, y

a piston on the lower end of said mandrel sealingly engaging theinterior of said housing,

a valve in said mandrel adapted to be operated between a first positionallowing ow through said mandrel and a second position cutting off owthrough the mandrel and providing communication between the interior ofthe mandrel above the valve and said annular space,

andv valve operator means carried by said mandrel adapted to operatesaid valve to said second position upon relative longitudinal movementof said mandrel and said housing to engage said hammer with said anvil,and to operate said valve to said iirst position upon opposite relativelongitudinal movement of said mandrel and said housing to a preselectedpoint.

3. A hydraulic jar as dened by claim 2 wherein said valve toperato-rmeans comprise-s an element mounted on said mandrel adapted to engagesaid housing upon movement of said hammer toward engagement with saidanvil whereby the mandrel moves upwardly relative to said element,

means eccentrically connecting said element to said valve, whereby saidvalve is rotated from said irst position to said second position inresponse to said relative movement of said element and said mandrel,

means responsive to said lrelative movement of said element and saidmandrel adapted to lock said eiement to said mandrel for movementtherewith in a direction to move said hammer and said anvil apart,

means on said housing positioned to `release said lock upon movement ofthe element and mandrel to a predetermined position, and v meansresiliently biasing said element toward upward movement relative to saidmandrel to rotate said valve to said first :position upon release ofsaid lock.

4. A hydraulic jar comprising a tubular housing, 4

a tubular mandrel telescopically received in said houslng cooperatingimpact surfaces on said housing and said mandrel,

means for applying tension to said mandrel to move the impact surfacestogether,

means responsive to the movement of the impact surfaces together fordirecting a pressure fluid between said mandrel and said housing to movethe impact surfaces apart and increase the tension on said mandrel,

and means responsive to the movement apart of said impact surfaces apredetermined distance for releasing said pressure fluid and allowingthe impact surfaces to strike each other.

5. A hydraulic jar comprising a pair of telescoping members adapted tobe connected in a drill string with one of said members connected to thedrill string above the jar and the other of said members connected tothe drill string below the jar,

, opposed impact surfaces on said members,

means in said jar for applying the pressure of the drilling mud flowingthrough the drill string in a manner to cause relative longitudinalmovement of said members in a direction to cause said impact surfaces tobe moved apart and said drill string to be stretched, and

means in said jar adapted to release said pressure upon completion of apredetermined amount of movement, whereby the drill string retracts `andthe impact surfaces strike each other.

6. A hydraulic jar comprising a tubular housing,

means on said housing for attachment to a pipe string,

an annular inwardly extending anvil in said housing,

a tubular mandrel telescopically received within said housingl andforming an annular space therebetween,

means on said mandrel for attachment 'to a pipe string,

an annular hammer on said mandrel,

means sealingly engaging said mandrel with said housing at both ends ofsaid annular space, and

valve means in said ymandrel actuable upon relative longitudinalmovement of said mandrel and housing in one direction to direct uidunder pressure to said annular space to cause said hammer and anvil tobe moved apart, and actuable upon relative longitudinal movement of saidmandrel and housing in the other direction to release the fluid fromsaid annular space to allow the hammer and anvil to move into engagementwith each other.

7. A hydraulicnjar as defined by claim and including an element on saidmandrel positioned to engage said housing as said hammer approaches saidanvil, said element being connected to said valve means and adapted tooperate said valve means, upon such engagement, to direct said uid tosaid annular space,

means on said mandrel resiliently biasing said element in a direction tooperate said valve means to release said fluid from said annular space,

cooperating means on said mandrel and said element adapted to lock saidelement against movement by said biasing means, and

means on said housing adapted to release said lock upon movement of saidhammer and said anvil a predetermined distance apart;

8. A hydraulic jar adapted to be connected in a drill string having apassageway therethrough for conducting drilling uid to a drill bitcomprising a tubular housing adapted to be connected at one end to saiddrill string,

a first impact surface in said housing,

a tubular mandrel telescopically slidably received in said tubularhousing and forming an annular space therebetween,

a passageway through said mandrel having substantially y the sa-mediameter as the drill string passageway,

means for connecting one end of said mandrel to said drill string,

a second impact surface on said mandrel positioned to strike said firstimpact surface upon longitudinal movement of said mandrel in onedirection with respect to said housing, v

means responsive to the movement of said impact surfaces together to cutoff the flow of drilling uid through said mandrel passageway and todirect it into` said annular space, whereby said mandrel is movedlongitudinally in another direction with respect to said housing andsaid impact surfaces are moved apart, and

means responsive to the movement apart of said impact surfaces apredetermined distance to release said drilling iiuid from said annularspace and allow said impact surfaces to move toward each other.

9. A hydraulic jar for connection between lower and upper portions of adrill string comprising a first tubular member having means thereon forconnection to the upper portion of the drill string,

a second tubular member telescopically engaging said rst tubular memberand having means thereon for connection to the lower portion of thedrill string,

opposed upper and lower impact surfaces on said members movable intocontact with each other upon upward movement of the upper portion of thedrill string relative to the lower portion,

valve means in one of said tubular members having a first positionallowing uid flow axially through the upper portion of the drill string,the inner tubular member, and the lower portion of the drill string, anda second position preventing uid fiow into the lower portion, and,

9 10 piston means connected to one of said tubular members 2,245,786 6/1941 Johnson 175-296 adapted to move said impact surfaces apart whensaid 2,344,725 3/ 1944 Phipps 175296 valve means is in said secondposition. 2,389,711 11/ 1945 Armentrout 175-296 2,622,372 12/ 1952Moulden 173-19 References Cited by the Examiner 5 2,969,771 1/ 1961Coudill 173-134 UNITED STATES PATENTS FRED C. MATTERN, IR., PrimaryExaminer. 1,569,183 1/1926 Herman etal. 175296 2,102,754 12/1937 Shannon175 296 L. P. KESSLER, Assistant Examinez'.

2. A HYDRAULIC JAR COMPRISING A TUBULAR HOUSING, MEANS ON THE LOWER ENDOF SAID HOUSING ADAPTED TO BE ATTACHED TO A PIPE STRING THEREBELOW, ADOWNWARDLY FACING INWARDLY EXTENDING ANNUAL ANVIL ADJACENT THE UPPER ENDOF SAID HOUSING, A TUBULAR MANDREL TELESCOPICALLY RECEIVED WITHIN SAIDHOUSING AND FORMING AN ANNULAR SPACE THEREBETWEEN, AN UPWARDLY FACINGANNULAR HAMMER ON SAID MANDREL, MEANS SEALINGLY ENGAGING THE UPPER ENDOF SAID HOUSING ABOUT SAID MANDREL, A PISTON ON THE LOWER END OF SAIDMANDREL SEALINGLY ENGAGING THE INTERIOR OF SAID HOUSING, A VALVE IN SAIDMANDREL ADAPTED TO BE OPERATED BETWEEN A FIRST POSITION ALLOWING FLOWTHROUGH SAID MANDREL AND A SECOND POSITION CUTTING OFF FLOW THROUGH THEMANDREL AND PROVIDING COMMUNICATION BETWEEN THE INTERIOR OF THE MANDRELABOVE THE VALVE AND SAID ANNULAR SPACE,